PRIMARY OBJECTIVE:
I. To evaluate the effect of metformin treatment on the expression of programmed cell death protein 1 (PD-1) on airway regulatory T cells (Tregs) in overweight and obese individuals at high risk for lung cancer.
SECONDARY OBJECTIVES:
I. Estimated PD-1 expression of pulmonary Tregs change in Cohort B during the wait period (26 weeks with no treatment).
II. To examine the impact of metformin on circulating immune cell subsets of blood.
EXPLORATORY OBJECTIVES:
I. To examine the impact of metformin on cancer-related transcriptome features of airway lesions.
II. To examine the impact of metformin on immune profile of pulmonary parenchyma represented by bronchoalveolar lavage (BAL).
III To examine the impact of metformin on histologic progression of abnormal airway lesions.
IV. To examine the impact of metformin on serum adipokines and inflammatory cytokines.
OUTLINE: Participants are randomized to 1 of 2 cohorts.
COHORT A: Participants receive metformin extended release (ER) orally (PO) once daily (QD) for 26 weeks in the absence of unacceptable toxicity. Participants undergo bronchoscopy biopsy and blood sample collection at screening, and week 13.
COHORT B: Participants receive no intervention for 26 weeks, then cross-over to cohort A. Participants undergo bronchoscopy biopsy and blood sample collection at screening, at week 26, and at 13 weeks after cross-over to Cohort A.
After completion of study treatment, participants are followed up at weeks 30-32 (Cohort A) and weeks 56-58 (Cohort B).